Responding to Senator Rozenboom (again)

A lesson about antioxidants.

Earlier in the year, I wrote a response to some of Senator Rozenboom’s comments in the Senate Agriculture Committee where he made some interesting claims based on his recent trip to the Netherlands. I pointed out that, contrary to his claims, nitrates have been a very serious issue in the Netherlands for decades and that the EU had a different way of representing nitrate concentration in water, which was the only plausible explanation I could think of for his claim that nitrates levels in Amsterdam were far higher than what we saw in Iowa last summer.

Senator Rozenboom, possibly triggered by comments yesterday from Senator Petersen asking Republicans if their legislation about having blue lights on boats would be their only water safety bill this year, again said a few things on the Senate floor that seem to be confused about the science around nitrates. He claimed the connection between nitrates and cancer is a “myth”, suggested that Republicans had been making great progress on Iowa’s water problems since 2017, and said that if you are really worried about nitrates you should look at the amount of nitrates in spinach. You can find the full video of his comments and the responses at this link but I’ve pulled out the relevant sections. Here’s the first relevant clip:

Ok, so in regards to the claim that the connection between nitrates and cancer is a “myth,” I would encourage people to read the recently released report from the Iowa Environmental Council and the Harkin Institute on Environmental Risk Factors And Iowa’s Cancer Crisis, particularly section 3, which meticulously documents numerous studies showing a connection between nitrates in drinking water and higher cancer risks. And of course I also have to suggest listening to my interview with Professor Thor Halderson, who chaired the scientific committee for the Denmark Ministry of the Environment that recommended lowering Denmark’s nitrate standards (which are similar to ours) by a factor of 10 because of the risk of colorectal cancers. Professor Halderson does a wonderful job describing their methodology and why the committee gave particular credence to a study that looked at over 1.2 million people with very precise numbers for nitrate levels in the water.

As for progress, Senator Rozenboom, as seems to be the norm for the current leadership, cited the amount of money spent by the government as the primary evidence for how much progress is supposedly being made on the issue.

However, as has been pointed out by Harkin Institute Senior Fellow John Norris in our recent report, the approach where “current policies measure success by how much money is spent on deployment of edge-of-field practices, not by clean water achieved” is clearly not working when you look at the actual water quality in Iowa. As Norris writes, we clearly need to switch to an approach where we “measure actual water quality outcomes, not just program participation”. In fairness, Senator Rozenboom did cite some additional statistics about cover crops, saturated buffers, and wetlands. However, these statistics can be misleading, since recent studies have found that, “of more than 3,200 Iowa farmers surveyed, about 20 percent who planted cover crops abandoned the practice a few years after adoption” and that “only 6.6 percent of cover crop users plant them consistently; nearly 30 percent are ‘intermittent adopters.’ Measuring positive field practices and land use changes is great, but we also need to pay attention to changes in the other direction! So the extent to which these policies can be counted as unambiguous “wins” seems to be an open question. But regardless, the central point remains: Iowa’s water quality problems are getting worse, not better, as was stated clearly in the Central Iowa Source Water Resource Assessment Report. If current leadership want to claim that we’re living in their version of utopia, that’s their right, but they shouldn’t be surprised if not many Iowans choose to follow them.

And finally, the most jaw-dropping claim made by Senator Rozenboom was the following:

 the last point that’s made here, and this is always rich to me, if you’re concerned about nitrates, I suggest you check out the nitrate levels in spinach

Considering that Senator Rozenboom was attacking the scientific credentials of medical doctor and State Representative Austin Baeth, who’s been doing an excellent job explaining the issues on social media, he really needs to do a better job looking at the science around nitrates. It’s pretty widely known that nitates in water have a very different impact than nitrates in fruits and vegetables that we consume, because the latter contain antioxidants that mitigate the effects of the nitrates. Quoting our report with IEC:

Experts believe that the source of nitrate is critical to determining its transformations in the body. When consumed with antioxidants, such as vitamin C found in fruits and vegetables, nitrate is more likely to be converted into beneficial, heart-healthy nitrogen oxides rather than nitrosamines. In contrast, foods high in added nitrates but low in antioxidants, such as cured meat, have a greater potential to form nitrosamines in the body (IARC, 2010; Karwowska & Kononiuk, 2020; Chazelas et al., 2022; Bowles et al., 2024)

If this is the science the current leadership is relying on to set their policies, it seems unlikely that Iowa will be addressing our cancer crisis anytime soon!

But on a more hopeful note, I’ll leave you with these excellent, extremely measured and diplomatic comments from Senator Janet Petersen, someone who has been very consistent about following the science. More of that please!